U.S. patent number 7,119,026 [Application Number 10/525,614] was granted by the patent office on 2006-10-10 for basic material for patterning and patterning method.
This patent grant is currently assigned to Sharp Kabushiki Kaisha. Invention is credited to Akiyoshi Fujii, Mitsuru Honda, Takaya Nakabayashi.
United States Patent |
7,119,026 |
Honda , et al. |
October 10, 2006 |
Basic material for patterning and patterning method
Abstract
A pattern forming method of the present invention includes the
steps of forming, on a substrate before droplets are ejected onto
the substrate, a water repelling area, in which a contact angle
between the droplet and the target surface is a first contact
angle, and a water attracting line, which is adjacent to the water
repelling area and in which a second contact angle is smaller than
the first contact angle and which is to be the pattern to be
formed; and landing droplets onto the target surface such that part
of the droplet landed is in a water repelling area and part of the
droplet landed is in a water attracting line, the equation (1) is
satisfied, D.ltoreq.L.times.{1+2(cos .theta..sub.2-cos
.theta..sub.1)} (1) where D is a droplet diameter, L is a pattern
width, .theta..sub.1 is a first contact angle, and .theta..sub.2 is
a second contact angle. By decreasing the number of discharged
droplets, it is possible to prevent increase of a tact time and
decrease of an inkjet operating life.
Inventors: |
Honda; Mitsuru (Sakurai,
JP), Nakabayashi; Takaya (Iga, JP), Fujii;
Akiyoshi (Nara, JP) |
Assignee: |
Sharp Kabushiki Kaisha (Osaka,
JP)
|
Family
ID: |
31972899 |
Appl.
No.: |
10/525,614 |
Filed: |
June 5, 2003 |
PCT
Filed: |
June 05, 2003 |
PCT No.: |
PCT/JP03/07169 |
371(c)(1),(2),(4) Date: |
February 24, 2005 |
PCT
Pub. No.: |
WO2004/023540 |
PCT
Pub. Date: |
March 18, 2004 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20050245079 A1 |
Nov 3, 2005 |
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Foreign Application Priority Data
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Aug 30, 2002 [JP] |
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2002-255610 |
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Current U.S.
Class: |
438/748;
438/750 |
Current CPC
Class: |
B41J
2/1433 (20130101); B41J 2/1606 (20130101); H05K
3/1241 (20130101) |
Current International
Class: |
H01L
21/302 (20060101); H01L 21/461 (20060101) |
Field of
Search: |
;438/748,750,752,753,754,756,757,FOR115 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0 930 641 |
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Jul 1999 |
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EP |
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63-200041 |
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Aug 1988 |
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JP |
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11-274671 |
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Oct 1999 |
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JP |
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2000-249821 |
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Sep 2000 |
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JP |
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2002-164635 |
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Jun 2002 |
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JP |
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WO 01/46987 |
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Jun 2001 |
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WO |
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WO 01/47045 |
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Jun 2001 |
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WO |
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WO 2004/021447 |
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Mar 2004 |
|
WO |
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WO 2004/023541 |
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Mar 2004 |
|
WO |
|
WO 2004/023561 |
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Mar 2004 |
|
WO |
|
Primary Examiner: Estrada; Michelle
Attorney, Agent or Firm: Neuner; George W. Conlin; David G.
Edwards Angell Palmer & Dodge LLP
Claims
The invention claimed is:
1. A pattern formation substrate on which a predetermined pattern
is formed by discharging droplets onto a target surface thereof,
the pattern formation substrate comprising: a first surface
containing the target surface comprising a first area and a second
area forming a pattern comprising a line of width L, the first area
being formed such that a droplet thereon exhibits a first contact
angle between the droplet and the first area, the second area being
formed such that a droplet thereon exhibits a second contact angle
between the droplet and the second area, wherein; when the droplet
is landed onto the target surface such that part of the droplet is
in the first area, and part of the droplet is in the second area,
which is adjacent to the first area, the second contact angle is
smaller than the first contact angle, and equation (1) is
satisfied, D.ltoreq.L.times.{1+2(cos .theta..sub.2-cos
.theta..sub.1)} (1) where D is a droplet diameter, .theta..sub.1 is
a first contact angle, and .theta..sub.2 is a second contact
angle.
2. A pattern forming method, comprising the steps of: providing a
pattern forming substrate comprising: a first surface containing
the target surface comprising a first area and a second area
forming a pattern comprising a line of width L, the first area
being formed such that a droplet thereon exhibits a first contact
angle between the droplet and the first area, the second area being
formed such that a droplet thereon exhibits a second contact angle
between the droplet and the second area, wherein; when the droplet
is landed onto the target surface such that part of the droplet is
in the first area, and part of the droplet is in the second area,
which is adjacent to the first area, the second contact angle is
smaller than the first contact angle, and equation (1) is
satisfied, D<L.times.{1+2(cos .theta..sub.2-cos .theta..sub.1)}
(1) where D is a droplet diameter, .theta..sub.1 is a first contact
angle, and .theta..sub.2 is a second contact angle; landing
droplets on the pattern forming substrate wherein one part of a
droplet can land on the first area and another part of the droplet
can land on the area on said pattern formation substrate, thereby
forming a pattern with the droplets.
3. The pattern forming method as set forth in claim 2, wherein the
first contact angle is set so that the first area becomes a
lyophobic area which is lyophobic against the droplets, and a
second contact angle is set so that the second area becomes a
lyophilic area which is lyophilic to the droplets.
4. A pattern forming method in which a predetermined pattern is
formed by discharging droplets onto a target surface, comprising
the steps of: forming a first area and a second area adjacent to
the first area before the droplet is discharged, the first area
being lyophobic against droplets, and the second area being
lyophilic to droplets and being to be the pattern to be formed; and
discharging the droplets onto the target surface so that a distance
x satisfy the equation 2, the distance x being a distance from a
border between the first and the second areas, to a center of a
landed droplet,
.ltoreq..times..times..times..times..theta..times..theta.
##EQU00008## where X is a distance between border of water
attracting/water repelling patterns and a center of a landing
droplet, D is a droplet diameter, and .theta..sub.1 is a contact
angle of an ink in a water repelling area.
5. A pattern forming method in which a predetermined pattern is
formed by discharging droplets onto a target surface, comprising
the steps of: forming a first area and a second area adjacent to
the first area before the droplet is discharged, the first area
being lyophobic against droplets, and the second area being
lyophilic to droplets and being to be the pattern to be formed; and
discharging the droplets onto the target surface so that a
discharging pitch P satisfy the equation (3), the discharging pitch
P being a pitch when the droplet is landed,
.times..ltoreq..ltoreq..times. ##EQU00009## where P is a
discharging pitch (.mu.m), D is a droplet diameter (.mu.m), L is a
water attracting line width (.mu.m).
6. A pattern forming method as set forth in any one of claims 2
through 5, wherein uninterrupted patterns are formed by unifying
droplets discretely landed onto the target surface.
7. A pattern forming method as set forth in any one of claims 2
through 5, wherein an inkjet head is used for discharging the
droplets.
8. A pattern forming method as set forth in any one of claims 2
through 5, wherein the first area and the second area are so formed
as to be substantially flat.
9. A pattern forming method as set forth in any one of claims 2
through 5, wherein the droplets contain electrically conductive
particles.
10. A pattern forming method as set forth in any one of claims 2
through 5, wherein the second area is a line-shaped pattern.
Description
TECHNICAL FIELD
The present invention relates to a pattern formation substrate on
which a predetermined pattern is formed by discharging droplets
onto a target surface, and also relates to a pattern forming
method.
BACKGROUND ART
In recent years, a wiring pattern of a substrate is formed by an
inkjet technology. A wiring pattern can be directly formed on a
substrate by the inkjet technology, so that high-cost processes,
such as vacuum deposition, photolithography, etching, and resist
removing process, can be omitted. As a result, a substrate can be
produced at low costs.
Incidentally, when a wiring pattern is formed by using an inkjet
head, fluid ink (droplets) containing a wiring material is jetted
out and landed on a predetermined position on a substrate. When the
droplets are discharged and landed on a substrate as above, there
is a possibility that the droplets spread too much or come off due
to the characteristics of a surface of the substrate. Therefore,
there is a problem that a desired wiring pattern cannot be
obtained.
In view of this, Japanese publication for Unexamined Patent
Application Tokukaihei, No. 11-204529, (published on Jul. 30, 1999)
discloses a method by which a desired wiring pattern can be formed
while suppressing spreading or coming off of landed droplets as
much as possible.
In the technology disclosed in the above publication, a surface of
a substrate is modified beforehand so that an area, in which a
wiring pattern may be provided, has affinity with droplets and the
other area does not have the affinity. Then, the wiring pattern is
formed by discharging droplets onto the affinity-having area
(pattern forming area) on a substrate. In this case, the area
except for the pattern forming area does not have affinity with
droplets. Therefore, the droplets, which land on the pattern
forming areas on a substrate, do not spread beyond the pattern
forming areas.
Further, in the technology disclosed in the above publication, the
droplets are discharged to be overlapped partially with each other
on the pattern forming areas so that the landed droplets do not
come off from the substrate. This prevents landed droplets from
coming off.
However, in the pattern forming method disclosed in the above
publication, the number of discharged droplets is large, because
the wiring pattern is formed by discharging the droplets so that
the droplets overlap partially with each other to prevent the
landed droplets on a substrate from coming off. In such a case,
there are problems that (i) a processing time (tact time) for a
series of steps until forming the wiring patterns will increase due
to an increase of the number of the droplets to discharge, and (ii)
an operating life of an inkjet head will be shortened.
The present invention was made to solve the above problems, and an
object of the present invention is to provide a pattern formation
substrate and pattern forming method which attains a satisfactory
wiring characteristics, while preventing an increase of a tact time
and an operating life shortening of an inkjet head by decreasing
the number of discharged droplets.
DISCLOSURE OF INVENTION
A pattern formation substrate of the present invention is so
arranged that a predetermined pattern is formed by discharging
droplets onto a target surface, and the pattern formation substrate
is formed to fulfill the equation (1) below when part of the
droplet lands on the first area and the other part of the droplet
lands on the second area. A contact angle of the first area, when
the above droplet lands on, is the first contact angle, and a
contact angle of the second area, which lies adjacent to the first
area, is the second contact angle which is smaller than the first
contact angle: D.ltoreq.L.times.{1+2(cos .theta..sub.2-cos
.theta..sub.1)} (1), where D is a droplet diameter, L is a pattern
width, .theta..sub.1 is a first contact angle, and .theta..sub.2 is
a second contact angle.
According to the above arrangement, because the second contact
angle is smaller than the first contact angle, the second area is
more lyophilic than the first area. With this arrangement, when a
droplet lands so that part of the droplet landed is on the first
area and the other part is on the second area, the part of the
droplet landed on the first area will move to the second area
(pattern) which is more lyophilic than the first area.
Furthermore, by setting a droplet diameter, a wiring pattern width,
the first contact angle, and the second contact angle so as to
fulfill the equation (1), droplets will be gathered into the second
area even if the droplet diameter is larger than the pattern
width.
By arranging to use droplets, whose diameter is larger than a
pattern width as such, the number of discharged droplets can be
reduced compared with when droplets, whose diameter is equal to or
smaller than a pattern width, is used.
By reducing the number of discharged droplets as above, it is
possible to prevent an increase of a tact time and a shortening of
an operating life of a droplet discharging mechanism, such as an
inkjet head or the like device.
When wiring patterns are formed with droplets which contain wiring
materials, each droplet does not overlap with each other on a
substrate if the number of discharged droplets decreases. In this
way, nonuniformity of wiring thickness, that is, nonuniformity of
wiring resistance can be reduced. As a result, it is possible to
obtain satisfactory wiring characteristics.
Further, it may be so arranged that the first contact angle is set
so that the first area becomes a lyophobic area which is lyophobic
against droplets, and the second contact angle is set so that the
second area becomes a lyophilic area which is lyophilic to
droplets.
In this case, the first area becomes a lyophobic area which is
lyophobic against droplets and the second area becomes a lyophilic
area which is lyophilic to droplets. Therefore, when a droplet
lands so that part of the droplet landed is on the first area and
the other part is on the second area, the droplet is repelled by
the first area which is a lyophobic area, and the droplet spreads
along the shape of the second area which is a lyophilic area is,
the droplet, which is repelled by the first area, flows to the
second area, and it spreads along the second area (pattern)
together with droplets which land on the second area, and forms
wirings.
Therefore, by arranging that an area that is not to be part of the
pattern, that is, the first area, is lyophobic against droplets, it
is possible to repel the landed droplets and to make droplets flow
to the second area.
If the first area is a lyophobic area and the second area is a
lyophilic area as described above, a difference between the first
contact angle and the second contact angle becomes large, and the
right side of the equation (1) becomes large. Here, the larger
right side of the equation (1) indicates that it is possible to use
droplets of a further larger droplet diameter in relation to a
wiring pattern width.
Therefore, the number of discharging droplets can be further
decreased by using the larger size of a droplet diameter in
relation to a wiring pattern width. As a result, it becomes
possible to decrease a tact time and prolong an operating life of a
droplet discharging mechanism such as an inkjet head.
Moreover, a pattern forming method according to the present
invention, in which a predetermined pattern is formed by
discharging droplets onto a target surface, includes the steps of
(i) forming a first area and a second area adjacent to the first
area before the droplet is discharged, the first area being
lyophobic against droplets, and the second area being lyophilic to
droplets and being to be the pattern to be formed, and (ii)
discharging the droplets onto the target surface so that a distance
X satisfy the equation (2), the distance X being a distance from a
border between the first and the second areas, to a center of a
landed droplet.
.ltoreq..times..times..times..times..theta..times..theta.
##EQU00001## where, X is a distance between a border of water
attracting/water repelling patterns and a center of a landing
droplet, D is a droplet diameter, and .theta..sub.1 is a contact
angle of ink in water repelling area.
In the above arrangement, droplets land onto a target surface so
that the distance X, which is the distance between the border of
water attracting/water repelling patterns and the center of landing
droplet, can fulfill the equation (2). According to this
arrangement, it is possible to move droplets, which land on the
first area which is a lyophobic area, to the second area which is a
lyophilic area. That is, it is possible to move droplets to the
second area even if the center of the droplets is not on the second
area.
With this arrangement, even when a low-precision droplet
discharging mechanism such as an inkjet head is used to discharge
droplets onto the substrate, droplets can surely be gathered to the
second area that is to be formed as a pattern. Thus, it is possible
to precisely form the pattern.
Therefore, it becomes possible to reduce the cost of an apparatus
which is for forming a pattern.
Here, the droplet can move in a wider range when the droplet is
larger as long as a pattern shape permits and a contact angle (the
first contact angle) of the droplet on the first area, which is a
lyophobic area, is small.
Furthermore, a pattern forming method according to the present
invention, in which a predetermined pattern is formed by
discharging droplets onto a target surface, includes the steps of
(i) forming a first area and a second area adjacent to the first
area before the droplet is discharged, the first area is lyophobic
against droplets, and the second area is lyophilic to droplets and
is to be the pattern to be formed, and (ii) discharging the
droplets onto the target surface so that a discharging pitch P
satisfies the equation (3), the discharging pitch P is a pitch when
the droplet is landed.
.times..ltoreq..ltoreq..times. ##EQU00002## where, P is a
discharging pitch (.mu.m), D is a droplet diameter (.mu.m), and L
is a water attracting line width (.mu.m).
With the above arrangement, by setting the droplet discharging
pitch P with respect to the droplet diameter and the pattern width
to fulfill the equation (3), it is possible to realize a pattern
which is more even in a line width and a line thickness.
In the case in which a predetermined wiring pattern is formed with
droplets which include wiring materials, a wiring pattern, which
has less nonuniformity of a line width and a line thickness and has
low resistance and small wiring difference in level, can be formed
with high throughput.
In this way, by setting the droplet discharging pitch to fulfill
the equation (3), it becomes possible to minimize the number of
discharged droplets, and also it becomes possible to decrease a
tact time and prolong an operating life of a droplet discharging
mechanism (inkjet head).
In addition, it is possible to arrange such that uninterrupted
patterns are formed by unifying droplets discretely landed onto the
target surface.
In this arrangement, since it becomes possible to minimize the
number of discharged droplets, it becomes possible to decrease a
tact time and prolong an operating life of a droplet discharging
mechanism.
An inkjet head may be used for discharging the above droplets.
In this arrangement, a multi-purpose inkjet head which is used for
a printer can be used as a droplet discharging mechanism. Thus, it
is possible to produce, at a low cost, an apparatus for forming
patterns.
The above first area and second area are so formed as to be
substantially flat.
In this case, "substantially flat" indicates a state that a
difference in level between the first area and the second area is
very small as compared with a pattern thickness to be formed. By
doing this, it is not necessary to form banks to make apparent
difference of affinity to droplets between the first area and the
second area. Therefore, the number of processes for a pattern
forming can be reduced.
The droplets can contain electrically conductive particles.
In this case, since a pattern, which is formed by discharging
droplets, becomes a wiring pattern, the wiring pattern, which has
no nonuniformity of a line width and a line thickness, can be
realized. Moreover, by decreasing the number of discharged
droplets, the droplets do not overlap with each other on a
substrate. In this way, it is possible to attain more uniform
wiring thickness, that is, uniform wiring resistance. As a result,
it is possible to obtain satisfactory wiring characteristics.
The above second area can be a line-shaped pattern.
In this case, a wiring forming can be realized by forming in a line
shape. Plus, a high wiring density can be realized by forming the
line pattern with an especially narrow width. Further, when applied
in wiring formation for a liquid crystal panel, a gate/source/drain
wiring should have the line shape. Especially, to improve panel
brightness, it is preferable that the line width is narrow because
the gate/source/drain wiring is made of a metal.
Additional objects, features, and strengths of the present
invention will be made clear by the description below. Further, the
advantages of the present invention will be evident from the
following explanation in reference to the drawings.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1(a) is a side view of a pattern formation substrate of the
present invention.
FIG. 1(b) is a plan view of the pattern formation substrate of the
present invention.
FIG. 2(a) is a diagram for explaining a water repelling property of
a droplet.
FIG. 2(b) is a diagram for explaining a water attracting property
of the droplet.
FIGS. 3(a) to 3(d) are diagrams illustrating steps of forming a
water attracting area and a water repelling area.
FIG. 4 is a graph illustrating a relation between a droplet
diameter and a pitch.
FIG. 5 is a schematic perspective diagram of a pattern forming
apparatus for use in a pattern forming method of the present
invention.
FIGS. 6(a) to 6(c) are diagrams illustrating another pattern
forming method of the present invention.
FIGS. 7(a) and 7(b) are diagrams illustrating yet another pattern
forming method of the present invention.
FIGS. 8(a) and 8(b) are diagrams illustrating still another pattern
forming method of the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention is explained further in detail by embodiments
and comparative examples. However, the present invention is not
limited to them.
(First Embodiment)
One embodiment of the present invention is explained below. Note
that, what is explained in the present embodiment is a pattern
forming method of a gate wiring of a TFT (Thin Film Transistor) in
a manufacturing process of a liquid crystal panel.
First of all, a pattern forming apparatus for realizing a pattern
forming method of the present invention is explained below.
As illustrated in FIG. 5, the pattern forming apparatus according
to the present invention includes a stage 12 on which a substrate
11 is to be mounted. On the stage 12, an inkjet head 13, a
Y-direction driving section 14, and an X-direction driving section.
15 are provided. The inkjet head 13 is droplet discharging means
for jetting out, onto the substrate 11, fluid ink (droplets)
including wiring materials. The Y-direction driving section 14
moves the inkjet head 13 in a y direction, and the X-direction
driving section 15 moves the inkjet head 13 move in the x
direction.
Moreover, the above pattern forming apparatus includes a droplet
supplying system 16, a liquid piping 18, and a device control unit
17. The droplet supplying system 16 and the liquid piping 18 supply
the droplets to the inkjet head 13, and the device control unit 17
performs various controls, such as controlling discharging of the
inkjet head 13, controlling driving of the Y-direction driving
section 14 and the X-direction driving section 15, and other
control.
The liquid piping 18 is provided between the inkjet head 13 and the
droplet supplying system 16, and droplet supply to the inkjet head
13 is controlled by the droplet supplying system 16.
Moreover, signal cables (not illustrated) are provided between the
device control unit 17 and the inkjet head 13, between the device
control unit 17 and the Y-direction driving section 14, and between
the device control unit 17 and the X-direction driving section 15.
The device control unit 17 controls discharging of the inkjet head
13 and driving of the Y-direction driving section 14 and the
X-direction driving section 15.
More specifically, the device control unit 17 gives (i) wiring
pattern information (Positional information for application) of the
substrate 11 to the y-direction drive section 14 and the
x-direction drive section 15 and (ii) ejection information to a
driver (not illustrated) of the inkjet head 13 in a synchronous
manner. This enables the droplets to be dropped on any positions of
the entire substrate 11.
As the above inkjet head 13, a piezo type or a thermal type is
adopted. The piezo type is a type that pushes out liquid (droplets)
from a nozzle by instantaneously increasing liquid pressure in an
ink bottle by using a piezoid which changes in shape by being
supplied with a voltage, and the thermal type is a type that pushes
out liquid by bubbles produced in liquid by using a heater attached
on a head. Both types of inkjet heads can adjust the diameter of
discharged droplets in response to the voltage applied to the
piezoid or the voltage applied to the heater.
In the present embodiment, in the above pattern forming apparatus,
a piezo driving type inkjet head, which includes a plurality of
nozzles whose diameter is 55 .mu.m, is used as the inkjet head 13.
The diameter of discharged droplets can be changed between 50 .mu.m
and 75 .mu.m by changing a driving voltage waveform.
Next, a method for forming a wiring pattern onto the substrate 11
by using the above pattern forming apparatus is explained below in
reference to FIGS. 1(a) and 1(b). FIG. 1(a) is a side view showing
a state of a droplet before landing onto a substrate and a droplet
after landing onto the substrate, and FIG. 1(b) is a plan view
showing a state of the droplet before landing onto the substrate
and the droplet after landing onto the substrate.
As illustrated in FIGS. 1(a) and 1(b), a pattern formation
substrate in accordance with the present embodiment is prepared by
forming, on the substrate 11, a water attracting line (the first
area) 6, which acts as a wiring pattern, and a water repelling area
(the second area). A droplet 8 whose diameter D is larger than a
line width L of the water attracting line 6 is discharged onto the
water attracting line 6, and the droplet 8 fits within the water
attracting line 6 by a change of an energy state that the droplet 8
has. Specifically, in the case in which the diameter D of the
droplet 8 is larger than the line width L of the water attracting
line 6, that part of the droplet 8, which lands on the water
repelling area 7, is repelled by the water repelling area 7. Thus,
the droplet 8 is gathered up within the water attracting line
6.
Note that, the surface of the substrate 11 is substantially flat
since the water attracting line 6 and the water repelling area 7
are realized by chemical process, which will be described later.
This can reduce the number of manufacturing steps as compared with
the conventional art in which a wiring pattern is formed by forming
banks.
By using the above pattern formation substrate, all droplets are
gathered up within wiring patterns even if droplets each having a
larger diameter than the width of a wiring pattern are used.
Therefore, a wiring pattern can be formed with a small number of
droplets. Further, if the number of discharged droplets is small,
it becomes possible to reduce a tact time and prolong an operating
life of the inkjet head.
First, the following discusses a case in which the droplet 8 whose
diameter is D is dropped onto the water attracting line 6 whose
line width is L, the water attracting line 6 sandwiched by the
water repelling area 7, as illustrated in FIG. 1(a). .theta..sub.1
is a contact angle when the droplet 8 lands on the water repelling
area 7 as illustrated in FIG. 2(a), and .theta..sub.2 is another
contact angle when the droplet 8 lands on the water attracting line
6 which is a water attracting area. When the droplet 8 lands on the
water attracting line 6 of the line width L sandwiched between the
water repelling areas 7, a contact angle is
.theta..sub.c(.theta..sub.1>.theta..sub.c>.theta..sub.2).
Moreover, where .gamma. is a surface energy of the droplet 8, an
energy .DELTA.W, which is consumed in response to the change of the
droplet 8 while a radius of the discharged droplet 8 is reduced by
x and the droplet 8 spreads along the water attracting line 6, is
approximately calculated by the equation below:
.DELTA.W=2D.gamma.(cos .theta..sub.2-cos .theta..sub.1)x
Where .DELTA.S is an increased amount of a surface area in response
to the change, a surface energy .gamma..DELTA.S of the droplet 8,
which increases in response to the change in shape, is
approximately calculated by the equation below:
.gamma..DELTA.S=.gamma.(D-L)Dx/L.
Therefore, the total energy .DELTA.E, which is a sum of the above
two, can be shown by the equation below:
.DELTA.E=.gamma.{D-L-2L(cos .theta..sub.2-cos
.theta..sub.1)}Dx/L
Here, when D-L-2L(cos .theta..sub.2-cos .theta..sub.1)>0, that
is, when L<D/{1+2(cos .theta..sub.2-cos .theta..sub.1)}, the
droplet 8 do not change in shape since .DELTA.E increases
monotonously in relation to the change in shape of the droplet
8.
On the other hand, when D-L-2L(cos .theta..sub.2-cos
.theta..sub.1)<0, that is, when L>D/{1+2(cos
.theta..sub.2-cos.sub.1)}, the droplet 8 keeps changing in shape
until all droplets fit within the water attracting line 6 because
.DELTA.E decreases monotonously in relation to the change in shape
of the droplet 8.
For example, when the second contact angle .theta..sub.2 is 0
degree and the first contact angle .theta..sub.1 is 90 degrees,
D<3L. Therefore, a wiring pattern can be appropriately formed
even if a droplet, whose diameter is up to three times as large as
a line width of the water attracting line, is used. In other words,
in this case, a wiring whose line width is 1/3 of the diameter of
the droplet can be formed.
Moreover, when the second contact angle .theta..sub.2 is 0 degree
and the first contact angle .theta..sub.1 is 180 degrees, D<5L.
Therefore, a wiring pattern can be appropriately formed even if a
droplet, whose diameter is up to five times as large as a line
width of the water attracting line, is used. In other words, in
this case, a wiring whose line width is 1/5 of the diameter of the
droplet can be formed.
Accordingly, by adjusting four parameters (.theta..sub.1,
.theta..sub.2, D, L) included in the above equation (1) to fulfill
the equation (1), it is possible to attain an appropriate
relationship between the droplet diameter D and the line width L of
a wiring pattern. For example, if a droplet diameter D is constant,
the first contact angle .theta..sub.1 and the second contact angle
.theta..sub.2 are adjusted to obtain a required line width L of a
wiring pattern.
Here, a concrete example of a wiring pattern formation is explained
below.
First, a surface modifying process onto the substrate 11, which is
performed before forming a wiring pattern, is explained below in
reference to FIGS. 3(a) to 3(d). FIGS. 3(a) to 3(d) are diagrams
illustrating respective steps of the surface modifying process for
the substrate 11 before the wirings are formed.
As illustrated in FIG. 3(a), by using a spin coat method, a
wettability variable layer 2 prepared from a silane coupling agent
or the like material is formed by coating a glass substrate 1 with
the silane coupling agent or the like material, and drying the
silane coupling agent or the like material on the glass substrate
1. Note that, in the present embodiment, as the wettability
variable layer 2, a ZONYL FSN (Product Name: provided by
Dupont-TORAY Co. Ltd.) is used, which is a fluorochemical nonionic
surfactant which had been mixed with isopropyl alcohol.
Next, as illustrated in FIG. 3(b), UV exposure is performed through
a photo mask 3 on which a mask pattern 4 constituted by chromium or
the like and a photocatalyst layer 5 constituted by titanium oxide
or the like are formed. Note that, in the present embodiment, the
photocatalyst layer 5 is formed by applying a mixture of a material
in which a titanium dioxide particle element is dispersed, and
ethanol by using the spin coat method, and then subjecting the
mixture to a heating treatment of 150.degree. C. Moreover, this
exposure is performed with a mercury lamp (wavelength: 365 nm) for
two minutes at illumination intensity of 70 mW/cm.sup.2.
As a result, as illustrated in FIGS. 3(c) and 3(d), wettability is
improved at a portion that is exposed to UV, thereby forming the
water attracting line 6. Note that, the width of the water
attracting line 6 formed in the present embodiment is set to be 50
.mu.m.
At this point, the areas except for the water attracting line 6
become the water repelling area 7. In this way, a water
attracting/water repelling pattern is formed on the substrate 11 as
a wiring pattern.
Then, a gate wiring is formed by dropping a gate wiring material,
by using the above pattern forming apparatus, onto the substrate 11
on which the water attracting/water repelling patterns are
formed.
A liquid wiring material (droplets), which was used for forming the
wiring, is prepared by dispersing Ag particles in mixture solvent
of water, ethanol and diethylene glycol. A viscosity was adjusted
to be about 10 cP beforehand. As illustrated in FIG. 2(a), the
first contact angle .theta..sub.1 of the droplet on the water
repelling area 7, which had been obtained by the above process, was
80 degrees, and as illustrated in FIG. 2(b), the second contact
angle .theta..sub.2 of the droplet on the water attracting line 6,
which had been obtained by the above process, was 10 degrees.
By using the above pattern forming apparatus, the droplet 8 is
dropped as illustrated in FIG. 1(a) onto the substrate 11 on which
water attracting/water repelling patterns are formed. When the
discharged droplet diameter D is 75 .mu.m, the discharged droplet 8
forms a line shape along the water attracting line 6 as illustrated
in FIG. 1(b). Note that, the landing position of the droplet 8 is a
center of the water attracting line 6.
Let the first contact angle .theta..sub.1=80 degrees and the second
contact angle .theta..sub.2=10 degrees in the above equation (1),
then: D.ltoreq.2.62L.
This shows that it is possible to form a line even when the droplet
diameter D is up to 2.62 times as large as the water attracting
line width L. That is, this indicates that a line whose line width
of 1/2.62 (.apprxeq.0.38) times of the droplet diameter D can be
formed.
Table 1 below shows results when the above droplets were dropped,
in the same condition as above, onto the water attracting lines 6
which had different widths respectively.
TABLE-US-00001 TABLE 1 LINE WIDTH (.mu.m) 75 50 30 20 RESULT
.largecircle. .largecircle. .largecircle. X .largecircle.: possible
to form lines, X: impossible to form lines
As shown in Table 1, it is impossible to form lines if the line
width is 20 .mu.m. When the line width is 20 .mu.m, 20/75
(.apprxeq.0.27), which is smaller than 0.38 mentioned above.
Therefore, the above equation (1) cannot be fulfilled in this case,
thereby making it possible to form lines.
Next, Table 2 below shows results when droplets, which had
different diameters respectively, were dropped onto the water
attracting lines 6 which had different widths respectively. Note
that, another inkjet head was used for the droplet diameter D of 35
.mu.m.
TABLE-US-00002 TABLE 2 LINE WIDTH (.mu.m) 30 20 15 10 DIAMETER: 65
.mu.m .largecircle. X X X DIAMETER: 50 .mu.m .largecircle.
.largecircle. X X DIAMETER: 35 .mu.m .largecircle. .largecircle.
.largecircle. X .largecircle.: possible to form lines, X:
impossible to form lines
As shown in Table 2, again, it was proved that, when the equation
(1) is not fulfilled, it is impossible to form lines.
Here, the relationship between the droplet diameter D and the
discharging pitch is explained below.
The pattern forming method, the gate wiring forming method, the
pattern forming apparatus and the inkjet head 13 was the same as
the above example. In addition, a liquid wiring material (droplet
8), which was used for forming wirings, was made by dispersing Ag
particles in water, and the viscosity was adjusted to be about 5 cP
beforehand. In this case, as illustrated in FIG. 2(a), the first
contact angle .theta..sub.1 of the droplet 8 on the water repelling
area 7 was 100 degrees, and as illustrated in FIG. 2(b), the second
contact angle .theta..sub.2 of the droplet 8 on the water
attracting line 6 was 10 degrees.
By using the above pattern forming apparatus, the droplet 8 is
dropped as illustrated in FIG. 1(a) onto the substrate 11 on which
the water attracting/water repelling pattern is formed. Note that,
the landing position of the droplet 8 is the center of the water
attracting line 6.
Table 3 below shows results when an ink material (droplets 8),
whose Ag concentration was 10 vol %, was dropped, with various
droplet diameters, onto the water attracting line whose width was
25 .mu.m. And the thickness of the ink material on the water
attracting line was set to be 0.3 .mu.m. A head was replaced when
the droplet diameter D was from 25 .mu.m to 45 .mu.m.
TABLE-US-00003 TABLE 3 DISTANCE FROM BORDER BETWEEN WATER
ATTRACTING AND WATER REPELLING (.mu.m) 40 50 100 110 DIAMETER: 75
.mu.m .largecircle. .largecircle. .largecircle. X DIAMETER: 35
.mu.m .largecircle. X X X .largecircle.: possible to form lines, X:
impossible to form lines
As shown in the result, it becomes possible to form lines by
fulfilling the equation (1). Moreover, the bigger the discharged
droplet diameter D is, the wider the discharging pitch can be used.
As a result, decreasing a tact time and prolonging an operating
life of a head can be attained.
The results in Table 3 are plotted in FIG. 4. The graph of FIG. 4
shows that, because pitches can be dramatically wider by using the
droplet diameter D of 50 .mu.m or more, it is preferable to set the
equation below for decreasing a tact time and prolonging an
operating life of a head: 2L.ltoreq.D.ltoreq.L{1+2(cos
.theta..sub.2-cos .theta..sub.1)}.
Further, the graph of FIG. 4 shows that, when a droplet diameter is
more than 54 .mu.m, it is possible to have a pitch 10 times wider
as compared with when a droplet diameter is the same as a line
width, whereby the tact time can be decreased to 1/10, and the
operating life of a head can be prolonged by 10 times.
Therefore, to decrease a tact time and to prolong an operating life
of a head, it is more preferable to set the equation as below:
2.15L.ltoreq.D.ltoreq.L{1+2(cos .theta..sub.2-cos
.theta..sub.1)}.
From this, it is found that it is possible to discharge the droplet
with a large diameter and a wide pitch by setting to fulfill,
D.ltoreq.L{1+2(cos .theta..sub.2-cos .theta..sub.1)}, preferably,
2L.ltoreq.D.ltoreq.L{1+2(cos .theta..sub.2-cos .theta..sub.1)},
more preferably, 2.15L.ltoreq.D.ltoreq.L{1+2(cos .theta..sub.2-cos
.theta..sub.1)}. Because of this, decreasing a tact time and
prolonging an operating life of head can be secured.
That is, the droplets 8 are discretely landed on the water
attracting lines 6 on the substrate 11, and each of the droplets 8
is connected with each other to form a continuous pattern. In this
way, since it becomes possible to minimize the number of droplets 8
to discharge, it becomes possible to decrease a tact time and
prolong an operating life of a droplet discharging mechanism (an
inkjet head).
Moreover, when the pitch of discharging droplets is set to be wide
to secure decreasing a tact time and prolonging an operating life
of a head, there is the case in which, when the line width to be
formed is partially narrow, the droplets do not fit within the
line. In this case, in response to the line width which needs to be
formed, the diameter of discharged droplets is changed by
controlling a driving waveform of a head. As a result, regardless
of the line width, it is possible to form line of any width with a
satisfactory tact time and a satisfactory operating life of a
head.
An example of changing a discharged droplet diameter in response to
a line width as such is explained in the second embodiment
below.
(Second Embodiment)
Another embodiment of the present invention is explained below.
Note that, a pattern forming apparatus as shown in the first
embodiment is used in the present embodiment so that it will not be
explained here.
Also in the present embodiment, a gate wiring pattern forming
method of TFT liquid crystal display panel is explained.
FIG. 6(a) illustrates a gate wiring pattern used in the present
embodiment. In this gate wiring pattern, a water attracting/water
repelling pattern is formed by a water attracting line 21 and a
water repelling area 22, and the line width of the water attracting
line 21 is not constant and is partially narrow. Specifically, the
water attracting line 21 has a water attracting line 21a through a
water attracting line 21d whose widths are respectively different.
Each of the widths of the water attracting line 21b and the water
attracting line 21c, which are narrower than that of the other
lines, is 20 .mu.m, and each of the widths of the other lines (the
water attracting line 21a and the water attracting line 21d) is 30
.mu.m. This water attracting/water repelling pattern is formed in
the same way as in the first embodiment.
Next, using an inkjet method, a gate wiring is formed by dropping
gate wiring materials onto a substrate on which water
attracting/water repelling patterns are formed. A pattern forming
apparatus and an inkjet head 13, which are used here, are the same
as those used in the first embodiment, and a diameter of each of
the discharged droplets can be changed from 50 .mu.m to 75
.mu.m.
In addition, a liquid wiring material (droplets) used here is the
same as those used in the first embodiment, and the first contact
angle .theta..sub.1 of the droplet on the water repelling area 22
was 80 degrees, and the second contact angle .theta..sub.2 of the
droplet on the water attracting line 21 was 10 degrees.
And, by using an inkjet head, the droplets 23 on the water
attracting line 21 are discharged as illustrated in FIG. 6(b). The
droplets each having a diameter of 75 .mu.m are discharged for
patterns whose line width is 30 .mu.m, and the droplets each having
a diameter of 50 .mu.m are discharged for patterns whose line width
is 20 .mu.m. By changing the droplet diameter in response to the
line width as above, it is possible to place the droplet 23 on the
entire water attracting line 21 (FIG. 6(c)).
Note that, when droplets each having a diameter of 75 .mu.m were
discharged onto a pattern whose line width was 20 .mu.m, the wiring
material did not fit within the pattern. When droplets each having
a diameter of 50 .mu.m were discharged onto an entire pattern, it
is possible to form lines, but the tact time increases as compared
with the case in which droplets each having a diameter of 75 .mu.m
were discharged for a pattern whose line width is 30 .mu.m.
Therefore, it is preferable that a droplet diameter be changed in
relation to each line width to fulfill the equation:
2L.ltoreq.D.ltoreq.L{1+2(cos .theta..sub.2-cos .theta..sub.1)},
more preferably, 2.15L.ltoreq.D.ltoreq.L{1+2(cos .theta..sub.2-cos
.theta..sub.1)}. By changing the droplet diameter, it becomes
possible to put droplets into patterns whose line width varies.
Furthermore, a satisfactory tact time and a satisfactory operating
life of a head can be obtained.
In each embodiment described above, droplets are discharged onto
the center of a water attracting line. To discharge droplets onto
the center of the water attracting line, it is necessary to use a
high-precision inkjet head. However, the high-precision inkjet head
is so expensive that there is a possibility of total price increase
of a pattern forming apparatus.
At this point, what is explained in the third embodiment is a
pattern forming method which can form lines on water attracting
lines even if droplets are not discharged onto the center of water
attracting lines.
(Third Embodiment)
Still another embodiment of the present invention is explained
below. Note that, as in the case of the first embodiment, the
present embodiment discusses an example in which wiring lines are
formed by using a water attracting/water repelling pattern which is
formed by water attracting lines 6 and water repelling areas 7. The
water attracting lines 6 and the water repelling areas 7 are formed
by modifying the surface of the substrate 11 by the surface
modifying processing method illustrated in FIGS. 3(a) and 3(d).
A pattern forming method in accordance with the present embodiment
is a method for moving the droplet 8 to within the water attracting
lines 6 as illustrated in FIG. 7(b) when the droplet 8 did not land
on the center of the water attracting lines 6 on the substrate 11
as illustrated in FIG. 7(a).
The inventors found out that, when the droplet 8 landed on the
substrate 11, the entire droplet 8 could move from the water
repelling area 7 into the water attracting line 6 as long as the
droplet partially lands on the water attracting line 6. That is, if
the distance from a border, which is between the water attracting
line 6 and the water repelling area 7, to a landing position of a
droplet 8 is shorter than a radius of a circular contact face of
the landed droplet 8, the entire droplet 8 can move from the water
repelling area 7 into the water attracting line 6,
R.sub.2=R.sub.1.times.3 {4/(2-3cos
.theta..sub.1-cos.sup.3.theta..sub.1)}, where the radius of a
droplet before landing is R.sub.1, the contact angle of a droplet
in a water repelling area is .theta..sub.1 and a radius of a
circular contact face when the droplet 8 landed is R.sub.2. When
the above R.sub.2 is converted into the droplet diameter D, the
equation (2) below is obtained:
.ltoreq..times..times..times..times..theta..times..theta.
##EQU00003## where X is a distance between a border of water
attracting/water repelling patterns and a center of a landing
droplet, D is a droplet diameter, and .theta..sub.1 is a contact
angle of ink in a water repelling area.
That is, when a pattern (which is not limited to a line shape) is
formed, using a water attracting/water repelling base pattern, by
an inkjet method, it is possible to move, as illustrated in FIG.
7(b), the droplet from the water repelling area 7 by setting, as
illustrated in FIG. 7(a), a landing position of a droplet 8 between
the water attracting/water repelling border 6a and a range defined
by the equation (2) below. Therefore, even when the landing
position of the droplet 8 is not on the water attracting line 6, it
is possible to move the droplet to a predetermined position.
Therefore, even when a low-precision inkjet head is used, a pattern
can be formed precisely. As a result, it is possible to attain a
low manufacturing cost of a pattern forming apparatus.
The droplet 8 can move in a wider range when the droplet 8 is
larger as long as a shape of a water attracting/water repelling
pattern permits and the contact angle of the droplet 8 with respect
to a water repelling 7 area is smaller.
.ltoreq..times..times..times..times..theta..times..theta.
##EQU00004## where X is a distance between a border of water
attracting/water repelling patterns and a center of landing
droplet, D is a droplet diameter, and .theta..sub.1 is a contact
angle of ink in a water repelling area.
Table 4 below shows results obtained with different landing
positions of droplets when the water attracting line width was 50
.mu.m. Note that, a liquid wiring material (droplets), which was
used for forming wirings, was made by dispersing Ag particles in a
mixed solvent of water, ethanol and diethylene glycol, and the
viscosity was adjusted to be about 10 cP beforehand. As illustrated
in FIG. 2(a), the first contact angle .theta..sub.1 of the droplet
8 on the water repelling area 7, which was obtained by the above
process, was 80 degrees, and as illustrated in FIG. 2(b), the
second contact angle .theta..sub.2 of the droplet 8 on the water
attracting line 6, which was obtained by the above process, was 10
degrees.
TABLE-US-00004 TABLE 4 DIAMETER D (.mu.m) 25 30 40 45 50 55 65 70
75 80 85 PITCH 0.11 0.19 0.45 0.64 0.87 1.16 1.92 2.39 2.94 3.57 X
(mm) X: impossible to form lines
It was found from Table 4 that, when the droplet whose diameter is
75 .mu.m is used, it is possible to form lines as long as the
droplet 8 is landed within a distance of 100 .mu.m from the water
attracting/water repelling border 6a, whereas, when the droplet
whose diameter is 35 .mu.m is used, it is possible to form lines if
the distance between the water attracting/water repelling border 6a
and the landing position is up to 40 .mu.m.
As above, the droplet discharging test with an inkjet head
confirmed that the entire droplet can move onto the water
attracting line as long as at least a part of a contact face of the
droplet is on the water attracting line. Thereupon, by setting the
droplet radius and the landing position beforehand as defined in
the above equation (2), a pattern can be formed precisely even when
a low-precision inkjet head is used.
(Fourth Embodiment)
Yet another embodiment of the present invention is explained below.
Note that, as is the case with the first embodiment, what is
explained in the present embodiment is an example that wiring lines
are formed by using a water attracting/water repelling pattern
which is formed with water attracting lines 6 and water repelling
areas 7. The water attracting lines 6 and the water repelling areas
7 are formed by modifying the surface of the substrate 11 by the
surface modifying processing method illustrated in FIG. 3(a) to
3(d).
The pattern forming method in accordance with the present
embodiment is explained below in reference to FIGS. 8(a) and 8(b).
FIG. 8(a) is a side view of the droplet 8 which is just before
landing, and FIG. 12(b) is a plan diagram of the droplet 8 which is
just before landing.
According to the pattern forming method of the present invention,
by setting a discharging pitch to fulfill an equation (3) below,
with respect to a discharging droplet diameter and a water
attracting line width on which a wiring is to be formed, it is
possible to form, with high throughput, a conductor pattern which
is more even in line width and thickness, and has low resistance
and small wiring difference in level.
.times..ltoreq..ltoreq..times. ##EQU00005## where P is a
discharging pitch (.mu.m), D is a droplet diameter (.mu.m), and L
is a water attracting line width (.mu.m).
The above equation (3) can be obtained as below.
Here, what is utilized in the pattern forming method in accordance
with the present embodiment is that a thickness of wirings can be
controlled by controlling a droplet diameter D and a discharging
pitch P in the case in which a pattern having a water attracting
line width L is formed on a substrate beforehand.
Therefore, to obtain the above equation (3), it is necessary to
obtain the values below by calculation.
(i) A total volume V of droplets, which can be obtained from the
droplet diameter D and the discharging pitch P (ii) A thickness of
a wiring, which can be calculated from the total volume V of
droplets and the water attracting line width L
(iii) A discharging pitch P, which can be calculated by a condition
of the thickness suitable for a pattern forming
Where P is the above discharging pitch (.mu.m), the dot number per
1 .mu.m is 1/P (dot/.mu.m).
In addition, where the droplet diameter is D, the total volume
V=.pi.D.sup.3/6. Therefore, the total volume per 1 .mu.m is:
1/P.times..pi.D.sup.3/6=.pi.D.sup.3/6P(.mu.m.sup.3).
Where the line width is L (.mu.m), the height of a droplet is
.pi.D.sup.3/6LP. Where Ag concentration is b (vol %), the height t
(.mu.m) of Ag is obtained by the following equation:
t=.pi.bD.sup.3/600LP.
If a droplet changes in shape, the discharging pitch
P=(.pi.b/600t).times.(D.sup.3/L).
The inventors found that, by setting .pi.b/600t no less than 0.04
and no more than 0.4 with respect to the discharging droplet and
the water attracting line width which forms lines, a wiring
pattern, whose line width and thickness has less nonuniformity and
which has low resistance and small wiring difference in level, can
be formed with high throughput.
Table 5 shows the result of a wiring forming when, in the above
pattern forming method, droplets each having a diameter of 75 .mu.m
are discharged onto a water attracting line whose width is 50 .mu.m
with various landing pitches. Numerical values in the table show a
thickness of the film in which the wiring was formed by
subsectioning, after an inkjet process, the liquid wiring material
to a heat of 250.degree. C. for ten minutes to dry off solvent and
to bake materials. Note that, the liquid wiring material used here
contained Ag particles in a ratio of 10% by volume.
TABLE-US-00005 TABLE 5 LANDING PITCH (.mu.m) 350 400 1500 3000 3500
RESULT .DELTA. .largecircle. .largecircle. .largecircle. X
(THICKNESS: .mu.m) (1.47) (1.10) (0.30) (0.15) (0.13)
.largecircle.: good wiring characteristics .DELTA.: no good since
wiring difference in level is too big X: no good since wiring
resistance is too big
From Table 5, it was found out that the appropriate wiring pattern
could not be obtained when the landing pitch was as narrow as 350
.mu.m, or as wide as 3500 .mu.m.
Likewise, Table 6 below shows results of a wiring forming when, in
the above pattern forming method, droplets each having a diameter
of 50 .mu.m were discharged with various landing pitches onto a
water attracting line whose width was 20 .mu.m. Numerical values in
the table show a thickness of the film in which wiring was formed
by subjecting, after an inkjet process, the liquid wiring material
to a heat of 250.degree. C. for ten minutes to dry off solvent and
to bake materials. Note that, the liquid wiring material used here
contained Ag particles in a ratio of 10% by volume.
TABLE-US-00006 TABLE 6 LANDING PITCH (.mu.m) 200 250 1000 2300 2600
RESULT .DELTA. .largecircle. .largecircle. .largecircle. X
(THICKNESS: .mu.m) (1.64) (1.31) (0.33) (0.14) (0.13)
.largecircle.: good wiring characteristics .DELTA.: no good since
wiring difference in level is too big X: no good since wiring
resistance is too big
From Table 6, it was found out that the appropriate wiring pattern
could not be obtained when the landing pitch was as narrow as 200
.mu.m, or as wide as 2600 .mu.m.
These findings show that an appropriate range of a landing pitch is
determined in relation to a water attracting line width and a
droplet diameter if a droplet material is the same.
In each embodiment described above, a liquid wiring material
(droplet) for forming a wiring was prepared by dispersing Ag
particles in a mixed solvent of water, ethanol and diethylene
glycol. Therefore, "lyophilic" is expressed as "water attracting",
and "lyophobic" is expressed as "water repelling". However, for
example, the solvent of the droplet wiring material may be
oil-based not water-based. In this case, "lyophilic" is expressed
as "lipophilic", and "lyophobic" is expressed as
"oil-repellent".
In addition, each embodiment described above explains the examples
using an inkjet method using an inkjet head as a mechanism for
discharging droplets onto a substrate which is a pattern formation
substrate. However, the present invention is not limited to this,
provided that the mechanism can control the droplet diameter and
discharge the droplets.
Moreover, an inkjet head is not limited to a piezo type, and may be
of a thermal type such as a bubble jet (registered mark).
Furthermore, it is acceptable if the second area (water attracting
line 6) formed on the substrate 11 has a line shape. In this case,
the line shape does not have to be lath-shaped as shown in each
embodiment described above, but may be meandering or tapered.
Moreover, the line can be a combination of these shapes. Further, a
contour of the line is not necessarily rectilinear, but can include
curves and zigzags.
In this way, a wiring forming can be realized by forming the water
attracting line 6 in the line shape. Plus, a high wiring density
can be realized by forming the line pattern with an especially
narrow width. Further, when applied in wiring formation for a
liquid crystal panel, it is essential that a gate/source/drain
wiring have the line shape. Especially, to improve panel
brightness, it is preferable that the line width be narrow because
the gate/source/drain wiring is made of a metal.
As described above, a pattern formation substrate of the present
invention is so arranged that a predetermined pattern is formed by
discharging droplets onto a target surface, and the pattern
formation substrate is formed to fulfill the equation (1) below
when part of the droplet lands on the first area and the other part
of the droplet lands on the second area. A contact angle of the
first area, when the above droplet lands on, is the first contact
angle, and a contact angle of the second area, which lies adjacent
to the first area, is the second contact angle which is smaller
than the first contact angle: D.ltoreq.L.times.{1+2(cos
.theta..sub.2-cos .theta..sub.1)} (1) where D is the droplet
diameter, L is the pattern width, .theta..sub.1 is the first
contact angle, and .theta..sub.2 is the second contact angle.
According to the above arrangement, because the second contact
angle is smaller than the first contact angle, the second area is
more lyophilic than the first area. With this arrangement, when a
droplet lands so that the droplet is on the first area and the
other part is on the second area, the part of the droplet on the
first area will move to the second area (pattern) which is more
lyophilic than the first area.
Furthermore, by setting the droplet diameter, the wiring pattern
width, the first contact angle, and the second contact angle so as
to fulfill the equation (1), droplets will be gathered into the
second area even if the droplet diameter is larger than the pattern
width.
By using droplets each having a diameter larger than a pattern
width, the number of discharged droplets can be reduced as compared
with when droplets each having a diameter equal to or smaller than
a pattern width, is used.
By reducing the number of discharged droplets as above, it is
possible to prevent an increase of a tact time and shortening of an
operating life of a droplet discharging mechanism, such as an
inkjet head.
Further, it may be so arranged that the first contact angle is set
so that the first area becomes a lyophobic area which is lyophobic
against droplets, and the second contact angle is set so that the
second area becomes a lyophilic area which is lyophilic to
droplets.
In this case, the first area becomes a lyophobic area which is
lyophobic against droplets and the second area becomes a lyophilic
area which is lyophilic to droplets. Therefore, when part of the
droplet lands on the first area and the other part of the droplet
lands on the second area, the droplet is repelled by the first area
which is a lyophobic area, and the droplet spreads along the shape
of the second area which is a lyophilic area. That is, the droplet,
which is repelled by the first area, flows to the second area, and
it spreads along the second area (pattern) with droplets which land
on the second area, and forms wirings.
Therefore, by arranging that an area that is not to be part of the
pattern, that is, the first area, is lyophobic against droplets, it
is possible to repel the landed droplets and to make droplets flow
to the second area.
If the first area is a lyophobic area and the second area is a
lyophilic area as above described, a difference between the first
contact angle and the second contact angle becomes large, and the
right side of the equation (1) becomes large. Here, the larger
right side of the equation (1) indicates that it is possible to use
droplets of a further larger droplet diameter in relation to a
wiring pattern width.
Therefore, the number of discharging droplets can be further
decreased by arranging such the droplets are greater in droplet
diameter in relation to a wiring pattern width. As a result, it
becomes possible to decrease a tact time and prolong an operating
life of a droplet discharging mechanism such as an inkjet head.
Moreover, the pattern forming method according to the present
invention, in which a predetermined pattern is formed by
discharging droplets onto a target surface, includes the steps of
(i) forming a first area and a second area adjacent to the first
area before the droplet is discharged, the first area is lyophobic
against droplets, and the second area is lyophilic to droplets and
being to be the pattern to be formed, and (ii) discharging the
droplets onto the target surface so that a distance x satisfy the
equation 2, the distance x is a distance from a border between the
first and the second areas, to a center of a landed droplet.
.ltoreq..times..times..times..times..theta..times..theta.
##EQU00006## where X is a distance between a border of water
attracting/water repelling patterns and a center of a landing
droplet, D is a droplet diameter, and .theta..sub.1 is a contact
angle of ink in a water repelling area.
Therefore, the droplets land onto a target surface so that the
distance X, which is the distance between the border of the first
area and the second area and the center of landing droplet, can
fulfill the equation (2). In this way, droplets, which land on the
first area which is a lyophobic area, can move to the second area
which is a lyophilic area. That is, it is possible to move droplets
to the second area even if the center of landing droplets is not on
the second area.
With this arrangement, even when a low-precision droplet
discharging mechanism such as an inkjet head is used to discharge
droplets onto the substrate, a pattern can be formed precisely
because the droplets can surely be flown to the second area which
is to be a pattern.
Therefore, the arrangement makes it possible to reduce the cost of
an apparatus for forming a pattern.
Furthermore, the pattern forming method according to the present
invention, in which a predetermined pattern is formed by
discharging droplets onto a target surface, includes the steps of
(i) forming a first area and a second area adjacent to the first
area before the droplet is discharged, the first area is lyophobic
against droplets, and the second area is lyophilic to droplets and
is to be the pattern to be formed, and (ii) discharging the
droplets onto the target surface so that a discharging pitch P
satisfy the equation (3), the discharging pitch P is a pitch when
the droplet is landed.
.times..ltoreq..ltoreq..times. ##EQU00007## where P is a
discharging pitch (.mu.m), D is a droplet diameter (.mu.m), and L
is a water attracting line width (.mu.m).
Therefore, by setting the droplet discharging pitch P with respect
to the droplet diameter and the pattern width to fulfill the
equation (3), it is possible to form the pattern with more evenness
in a line width and a line thickness.
When the droplet contains a wiring material and a wiring pattern is
formed as a predetermined pattern, it is possible to form, with
high throughput, the wiring pattern which has less nonuniformity of
a line width and a line thickness and has low resistance and small
wiring difference in level.
In this way, by setting the droplet discharging pitch to fulfill
the equation (3), it becomes possible to minimize the number of
discharged droplets required for forming the pattern, and also it
becomes possible to attempt to decrease a tact time and prolong an
operating life of a droplet discharging mechanism (inkjet
head).
The embodiments and concrete examples of implementation discussed
in the foregoing detailed explanation serve solely to illustrate
the technical details of the present invention, which should not be
narrowly interpreted within the limits of such embodiments and
concrete examples, but rather may be applied in many variations
within the spirit of the present invention, provided such
variations do not exceed the scope of the patent claims set forth
below.
INDUSTRIAL APPLICABILITY
A pattern formation substrate and a pattern forming method of the
present invention are in a field that a wiring pattern on a
substrate is formed by an inkjet technology, and especially, can be
suitably used in a field that needs prolonging inkjet heads and
reducing the manufacturing cost.
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